1. Cross-Reference to Related Applications
This application is related to Utility patent application Ser. No. 10/324,908, filed Dec. 20, 2002, entitled METHOD AND APPARATUS FOR ACCOMMODATING HIGH BANDWIDTH DATA TRAFFIC ON A WIRELESS NETWORK, the content of which is hereby incorporated herein by reference.
2. Field of the Invention
The present invention relates to high bandwidth wireless communications and, more particularly, to a method and apparatus for enabling high bandwidth data transmissions over wireless communication networks.
3. Description of the Related Art
Wireless communication networks have been deployed in many areas. While these wireless communication networks have data rates sufficient to handle voice traffic, as higher bandwidth data-centric applications are deployed and implemented, the existing deployed technology base is likely to be unable to accommodate the increased demand in bandwidth.
There are currently two basic technologies in use in second generation wireless communications networks. In Europe, parts of the United States, and most of the rest of the world, wireless transmissions are based on a technology referred to as Time Division Multiple Access (TDMA). TDMA divides an available channel into time slots and interleaves multiple digital signals onto a single high-speed channel. One popular wireless technology based on TDMA is referred to as Global System for Mobile Communications (GSM). GSM is a circuit-switched system that divides each 200 kHz channel into eight 25 kHz time slots.
In the United States and certain parts of Asia, wireless transmissions are based on a technology referred to as Code Division Multiple Access (CDMA), which is a method for transmitting simultaneous signals over a shared portion of the spectrum. Unlike TDMA, which divides the spectrum into different time slots, CDMA's spread spectrum technique overlaps every transmission on the same carrier frequency by assigning a unique code to each conversation. After the speech codec (coder-decoder) converts the analog voice signal to a digital signal, the CDMA system spreads the digital voice stream over the full 1.25 MHz bandwidth of a CDMA channel, coding each stream separately so it can be decoded at the receiving end. All voice conversations thus use the full bandwidth at the same time. One bit is multiplied into 128 coded bits by the spreading techniques, providing the receiving side with a large amount of data that can be averaged to determine the value of each bit when correlated with the appropriate code.
GSM and (Interim Standard) IS-95A (code name for CDMA wireless currently deployed in the United States) are both optimized for voice transmission. Voice transmission is characterized by transmission that requires a relatively constant regular amount of bandwidth, but which is not particularly bursty. GSM and IS-95A are not optimized, however, for data transmission which tends to be very bursty with a relatively low average data rate.
Several transmission standards are in the process of being developed to enable wireless networks to be deployed that can accommodate higher bandwidth data transmissions as well as voice. In the TDMA-based wireless space, the evolving technology is Wideband CDMA (W-CDMA). W-CDMA is a third generation (3G) technology that increases data transmission rates in GSM systems by using a CDMA air interface instead of the TDMA interface. In the ITU's IMT-2000 3G specification, W-CDMA has become known as the Direct Sequence (DS) mode.
Universal Mobile Telecommunications System (UMTS) is the European implementation of W-CDMA that is planned to form the basis of the 3G wireless phone system in Europe. UMTS, which is part of IMT-2000, provides service in the 2 GHz band and offers global roaming and personalized features. The UMTS specification calls for support of multimedia data rates of up to 2 Mbps using the W-CDMA technology. In the meantime, General Packet Radio Service (GPRS), which modifies GSM to support data packets up to 114 Kbps, and Enhance Data Rates for Global Evolution (EDGE), which increases data throughput to 384 Kbps, are interim steps to speed up wireless data for GSM.
In the IS-95A CDMA space in use in the United States, the technology is evolving toward CDMA-2000, a 3G wireless technology that offers twice the voice capacity and data speed (up to 307 Kbps) on a single 1.25 MHz (1X) carrier in new or existing spectrum. CDMA2000 1X is also known as IS-2000, MC-1X and IMT-CDMA MultiCarrier 1X and 1xRTT (Radio Transmission Technology). The interim standard in the United States is IS-95B, which provides data capabilities up to 64 Kbps integrated with voice.
CDMA2000 1xEV is an evolution of CDMA2000 that provides higher speeds on a single 1.25 MHz channel. CDMA2000 may also be deployed in a 5 MHz channel, which is three times (3X) the carrier rate of CDMA2000 1X. CDMA2000 3X is also known as MC-3X, IMT-CDMA MultiCarrier 3X and 3xRTT.
While implementing one or more of these proposed protocols may, at some point in time, enable the simultaneous transmission of voice and data, obtaining the required licenses and upgrading or retrofitting existing networks will take time and a significant investment. Additionally, in many of these proposed standards, the high bandwidth data capabilities exist at the expense of the low-bandwidth voice services, e.g., to obtain 100 Mbps of data capacity the system may lose 100 Mbps or more of voice capacity.
Additionally, the delay associated with obtaining bandwidth for data bursts in many of the protocols is relatively high, due mainly to theoretical limitations associated with the physical medium and practical limitations associated with protocol implementation. On the downlink side where codes are allocated in line with the negotiated bandwidth, the problem is somewhat more severe because of the limit to codes that can be allocated. These delays may be disconcerting to an user, especially where the delays are inconsistent or unpredictable. Accordingly, it would be advantageous to have a high data rate burst mode transmission capability at a predictable delay that could be interleaved with voice services, while largely maintaining the network's voice capacity.